| Abstract: | Specifically 18O]-labelled γ-valerolactone and 4-methyl-γ-valerolactone were submitted to tracer equilibration in dilute mineral acid at reflux temperature. Though under these conditions the two lactones are known to be hydrolyzed to the extent of about 25% to the corresponding γ-hydroxy acids only the «tertiary» 4-methyl derivative lost its alkoxyl label whereas the unsubstituted «secondary» one retained it. – This may be understood on the base of two alternative mecanisms possible for lactone reformation. The results permit a quantitative evaluation of the amount of carboxyl-participation during acid hydrolysis of 4-substituted carboxylic acids to 4-monoalkylated γ-butyrolactones. |
